Objective      To determine the effect of carbon nanoparticles-epirubicin suspension (CNP-EPI) on the proliferation and apoptosis in human breast cancer MDA-MB-231 cells.       Methods      MDA-MB-231 cells were cultured with different concentrations of CNP-EPI in vitro. CCK-8 assay was used to determinate the inhibitory effect of CNP-EPI on the proliferation of M

DA-MB-231 cells at different concentrations and for different times. According to the determination of IC

50

5 μg/mL CNP-EPI (25 μg/mL CNP) and only add culture medium were selected

and the cell morphology was observed with inverted microscopy

and cell apoptotic rates were determined by flow cytometry after 24 hours’ treatment.       Results      CNP-EPI exerted gradually stronger inhibitory effect on the proliferation of MDA -MB-231 cells in a dose-dependent manner when the concentration ranged from 1 to 200 μg/mL for same time period

and the inhibitory effect was still in a increasing trend after 48 hours’ treatment

but slowly turned to stable. The inhibitory effect of CNP-EPI was significantly stronger in CNP-EPI treated cells than in normal control cells at all time points (P0.01). However

no such inhibitory effect was found in the MDA-MB-231 cells treated by different concentrations of CNP. For the cells treated by 5 μg/mL CNP-EPI for 24 h

inverted microscopy observed that a great deal of cells were dead

but no obvious change of cell morphology was seen in the control cells and the cells treated by CNP. Flow cytometry indicated that the apoptotic rate was (14.37±6.25) % and the mortality reached to (80.70±6.20) % in the cells treated by 5 μg/mL CNP-EPI group for 24 h

which were significantly higher than those of CNP-treated cells and normal control cells (P0.05).       Conclusion      CNP-EPI exerts obviously inhibitory effect on the proliferation or killing effect in the human breast cancer MDA-MB-231 cells. The inhibitory effect of CNP-EPI might be due to delayed releasing of EPI to directly kill the tumor cells or induce cell apoptosis.